Synchronization in television and facsimile transmission system



Sept. 22, 1931. A. c. STOCKER 1,824,635

SYNCHRQNIZATION IN TELEVISION AND FACSIMILE'TRANSMISSION SYSTEM Filed Oct. 21, 1930 Fig. I

Dela l lpparafus Transmission 1 4 synchronizing T rans/miffer fi yfifem I I flpplir'afus /L J@J Invntor": Arthur' C. Stocker;

m ma/afa His Attorney.

cable to such systems where rence of such transient phenomena is less Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE ARTHUR C. STOCKER, OI! AUDUBON, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK SYNCHRONIZATION IN TELEVISION .AND FACSIM'ILE TRANSMISSION SYSTEM Application filed October 21, 1980. Serial No. 490,237.

My invention relates to television and facsimile transmission systems and particularly to the synchronization of the transmitting and receiving apparatus of such systems. In

| the past, synchronization commonly has 10 and using it to control the speed of the receiver. Since the instantaneous value of that voltage determined the instantaneous position of the scanning apparatus of the receiver, an transient phenomena such as is static, switc ing surges, etc. may'cause the receiver to swing or hunt and may even cause it to fall out of step.

It is the object of my invention to provide an improved method and apparatus appliy the occurliable to produce an objectionable effect on the receiver. In carrying out my inventio 1 in accordance with the form thereof which I have chosen to illustrate, I employ as before a synchronizing signal comprisin regularly recurring impulses which is pro need at the transmitter and transmitted to the receiver.

3 At the receiver I divide the signal into two parts. One part I delay one or more whole number of cycles according to convenience and then combine the two parts to make up the complete signal according to which the synchronization is efi'ected. Thus, with a sinusoidal or other perfectly recurrent signal voltage transmitted, the voltage delivered to the synchronizer would remain apo parently unchanged. -Any transient phe-' nomena picked up in the transmission, be-' ing of a non-recurrent character, would be delivered to the synchronizer as two such phenomena, each of half value, and separated by a time equal to the time lag of the delaying apparatus. Synchronization is thus made steadier and less liable to failure due to the occurrence of transients. The possibility of two similar transients occurring at a time interval equal to the time lag of the delay apparatus is so remote that such an occurrence may be neglected.

My invention will be better understood from the following description taken in connection with the accompanying drawings, and its scope will'be pointed out in the appended claims.

Referring to the drawings, Fig. 1 is a block diagram of a system involving my invention and Fig. 2 is a detail thereof.

In Fig. 1, I have represented 'at 1 the transmitter of the system; 2 represents the transmission system which may be radio, wire line or any other transmitting means; 3 represents the signal divider forming a part of the receiver. By means of the si nal divider the receiver signal is divided in the present case'into two parts, one of these parts is subjected to the effect of the delay apparatus 4 which, as has already been pointed out, causes a delay in the signal of one or more whole number of cycles. The two parts of the divided signal thereafter are united by the signal uniter 5 and the complete signal is then employed in the synchronizing apparatus 6 to control the speed of the receiver.

The time delay apparatus 4 may comprise any well known form of apparatus suitable for this purpose. In Fig, 2, I have illustrated one form of apparatus that may be employed. In accordance with this figure,

the signal divider comprises the transformer shown a well known form of attenuatorwhich is represented ascomprising the series non-inductive resistances 17 and the parallel resistance 18. It will be understood 100 that the purpose of the attenuator just described is only to effect the same attenua- .two parts, delaying one tion in both parts of the signal.

While I have chosen to illustrate and describe my invention in its simplest form, namely, that in which the signal is divided into two parts one of which is delayed, it is not limited to such form inasmuch as the signal may, if desired, be divided into a greater number of parts of which a plurality of parts are caused to be delayed each a difi'erent number of whole number of c cles. Moreover if desired both or all of t e parts may be delayed different whole numbers of cycles.

Various modifications may therefore be made without departure from the spirit and scope of my invention which modifications I aim to cover by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States,

1. In a television or facsimile transmission system employing a synchronizing signal comprising regularly recurring impulses, the method of reducing the effect of transient phenomena on the synchronization which comprises dividing the synchronizing signal at the receivin station into a plurality of parts, producing a phase dislacement of one ofsaid parts a whole numr of cycles and recombining the parts to' make up a complete signal by which the synchronization is effected.

2. In a television or facsimile transmission system employing a synchronizing signal comprising regularly recurring impulses,

the synchronization which comprises dividmg the signal at the receiving station into art a whole number of cycles, and recom ining the parts to make up the complete signal by which the synchronization is effected.

4, In a television or facsimile transmission system employing a synchronizing signal comprising regularly recurring impulses, means at the receiving station of said system for dividing the synchronizing signal into a plurality of parts, means producing a phase displacement of one of said 5. In a television or facsimile transmission system employing a synchronizin signal comprising an alternating vo tage, means at the receivin station of said system providing a divi ed path for the synfor producing an attenuation substantially equal to that in the one branch, and means for uniting the signals of said branches.

In witness whereof, I have hereunto set my hand this 16th day of October, 1930. I ARTHUR C. STOCKER.

parts a whole number of impulse cycles and means for recombining said parts to form acomplete synchronizi ng signal. 

